Patricia Leonardi | Universidad Nacional del Sur (original) (raw)

Papers by Patricia Leonardi

Journal of Applied Phycology, 2013

The diversity of epiphytes, their temporal abundance variation and the anatomical structure of ho... more The diversity of epiphytes, their temporal abundance variation and the anatomical structure of host-epiphyte interfaces were studied in the agarophyte Gracilaria gracilis from a natural bed in Bahía Bustamante, Chubut Province, Argentina. Twenty-nine algal species were recorded as epiphytes during 2 years of monthly sampling (March 2006-February 2008. Total epiphyte density ranged between 0.037 ind. cm −2 (November 2006) and 39.37 ind. cm −2 (April 2007), with higher density values throughout the second sampling year. Ceramiales species were the most abundant epiphytes. The density of Ceramium rubrum ranged from 0.09 ind. cm −2 (52 % of the total amount) in September 2006 to 17.4 ind. cm −2 (44.18 % of the total amount) in April 2007. Epiphyte infection was more dependent on spore recruitment and sporeling development, especially on thalli derived from fragmentation, than on seasonal environmental variations.

Revista de la Sociedad Argentina de Biología

Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of d... more Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of detached thalli cast on the shore. Therefore, the study of carpospores is relevant because such spores can be used as inoculum for commercial aquaculture. In this study, the potential of two natural substrates from the Patagonian coast, for the settlement and growth of G. gracilis carpospores, was evaluated in the laboratory. Highly significant differences were found between substrates both in the proportion of substrates with settled spores and in carpospore density, shells being more suitable than pebbles. Regarding carposporeling growth, differences in sporeling length between substrates could not be detected by the end of the study, although basal discs reached a significantly higher diameter on pebbles than on shells. Results indicate that shells would be a good substrate to start spore culture because they offer a suitable surface for spore settlement. In addition, if the substrate is inoculated with sufficient seedling material to avoid competition among individuals and, if epiphytism is successfully reduced, sporelings should reach the required size for transport to the natural environment.

Biocell: official journal of the Sociedades Latinoamericanas de Microscopía Electronica ... et. al

This is the first comprehensive ultrastructural study on dwarf males with external gametangia in ... more This is the first comprehensive ultrastructural study on dwarf males with external gametangia in the genus Oedogonium, from androspore germination to the liberation of mature male gametes. The ultrastructure of the process in O. macrandrium Wittrok is similar to that of Bulbochaete hiloensis (Nordstedt) Tiffany, but with two remarkable differences. In O. macrandrium : 1) instead of a true transverse wall, only condensed mucilage appears between the gametes of each antheridial cell, and 2) the cell wall between the basal cell and the basal most antheridial cell has sim-the cell wall between the basal cell and the basal most antheridial cell has simple plasmodesmata similar to those present in the transverse walls of vegetative cells, which are absent in B. hiloensis.

Aquatic Botany, 2015

The ultrastructure of vegetative internodal cells in a representative of the genus Tolypella (sec... more The ultrastructure of vegetative internodal cells in a representative of the genus Tolypella (section Rothia) is described for the first time for Tolypella intricata. The most striking difference compared with the cells of Chara and Nitella is that the four-layered lateral cell wall shows the regular presence of unique refractive lenticular thickenings, which we designate as "tolysomes", considering their unique ultrastructure elucidated here for the first time. Tolysomes greatly amplify the plasma membrane surface; thereby defining particular spaces of the cytoplasm. There are similar structures in the cell walls of the non-charalean charophyte Coleochaete orbicularis and also in bryophytes, angiosperms and gymnosperms. As the function of tolysomes is hitherto elusive, a bona fide analysis of evolutionary significance is not yet possible. C-shaped amitotic nuclei are similar to those described for young internodal Chara cells. Resting amitotic nuclei exhibit normal nuclear envelope, dispersed granular chromatin and numerous nucleoli with variable size. Nevertheless, they show neither the single, central nucleolus characteristic of dividing Chara nuclei nor the bundles of tubular elements running parallel to the long axis of the nucleus, which are also normal in Chara and Nitella amitotic nuclei. The presence of C-shaped resting nuclei of Tolypella and Chara and their absence in Nitella and the presence of spindle-shaped nuclei in Nitella, but not in Tolypella, suggest that Tolypella (section Rothia) divergence took place earlier than did Nitella in accordance with, but also in contradiction to molecular data. Mature echinoid bodies and chloroplasts in Tolypella intricata are entirely similar to those previously described for Chara and Nitella.

Journal of Phycology, 2000

Journal of Phycology, 2000

Page 1. PSA ABSTRACTS 1 1 FATTY ACIDS IN PHOTOTROPHIC AND MIXOTROPHIC GYRODINIUM GALATHE-ANUM (DI... more Page 1. PSA ABSTRACTS 1 1 FATTY ACIDS IN PHOTOTROPHIC AND MIXOTROPHIC GYRODINIUM GALATHE-ANUM (DINOPHYCEAE) Adolf, JE1, Place, AR2, Lund, E.2, Stoecker, DK1, & Harding, LW, Jr 1,3 1Horn Point ...

Botanica Marina, 2000

Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of d... more Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of detached thalli cast on the shore. Therefore, the study of carpospores is relevant because such spores can be used as inoculum for commercial aquaculture. In this study, the potential of two natural substrates from the Patagonian coast, for the settlement and growth of G. gracilis carpospores, was evaluated in the laboratory. Highly significant differences were found between substrates both in the proportion of substrates with settled spores and in carpospore density, shells being more suitable than pebbles. Regarding carposporeling growth, differences in sporeling length between substrates could not be detected by the end of the study, although basal discs reached a significantly higher diameter on pebbles than on shells. Results indicate that shells would be a good substrate to start spore culture because they offer a suitable surface for spore settlement. In addition, if the substrate is inoculated with sufficient seedling material to avoid competition among individuals and, if epiphytism is successfully reduced, sporelings should reach the required size for transport to the natural environment.

Bioresource Technology, 2009

Milled summer thalli of Gracilaria gracilis from Argentina were sequentially extracted with water... more Milled summer thalli of Gracilaria gracilis from Argentina were sequentially extracted with water at room temperature (RTW1-3), 70°C (W701-3) and 90°C (W901-2). Both W701 and W901 consisted of high molecular weight polysaccharides (ca. 540,000 Da), but polydispersity was higher for the major product W701 (yield, 72% of the recovered). Structural analyzes by methylation and 13 C NMR spectroscopy revealed that W701 was mainly agarose. Alkaline treatment, together with structural analyzes, indicated a negligible proportion of precursor L-galactose 6-sulfate residues in this product, while they were clearly detected in the 13 C NMR spectra of RTW2-3. The presence of floridean starch in W901 had an antagonistic effect on its gel strength, which resulted nearly three times lower than that of fraction W701.

Darwiniana, 2003

... Academic Press, London, Orlando. Lokhorst, GM, Bakker, ME & Star, W. 1984. Ultrastructure... more ... Academic Press, London, Orlando. Lokhorst, GM, Bakker, ME & Star, W. 1984. Ultrastructure of Draparnaldia glomerata (Chaetophorales, Chlorophyceae) II. Mitosis and cytokinesis. Nord. J. Bot. 4: 553-562. ... Arch. Protistenk. 112: 365-375. McLean, RO & Benson-Evans, K. 1977. ...

Phycological Research, 2013

Seasonal variation of agar from specimens of a commercially exploited population of Gracilaria gr... more Seasonal variation of agar from specimens of a commercially exploited population of Gracilaria gracilis (Stackhouse) Steentoft, Irvine & Farnham in the Patagonian coast of Argentina was studied. For each seasonal harvest, random samples of plants were pooled for subsequent polysaccharide extraction at different water temperatures and agar physico-chemical properties and composition were determined.

Journal of Phycology, 2000

The ultrastructure of zoospores of Asterococcus superbus (Cienk.) Scherffel was studied to provid... more The ultrastructure of zoospores of Asterococcus superbus (Cienk.) Scherffel was studied to provide ultrastructural data relevant to the systematic position of the genus. Our results demonstrated that the motile cells of A. superbus were similar to those of the tetrasporalean algae, such as Tetraspora sp. and Tetrasporidium javanicum Moebius . The flagellar apparatus of A. superbus had the same clock-wise orientation of basal bodies and the V-shaped alignment of basal bodies as Tetraspora cylindrica (Wahlb.) Ag. and T. lubrica (Roth) Ag., but differed by having rhizoplasts . The motile cells of A. superbus displayed chlamydomonadal ultrastructure, similar to Chlamydomonas reinhardtii Dangeard , including the absolute configuration of the flagellar apparatus. The pyrenoid matrix in A. superbus, however , showed a large lateral invagination occupied by chloroplast stroma, a characteristic that has never been observed in Chlorophyta.

Phycologia, 2007

ABSTRACT The chemical composition of the sporophyte cell wall of Adenocystis utricularis was exam... more ABSTRACT The chemical composition of the sporophyte cell wall of Adenocystis utricularis was examined by using a number of histochemical techniques for the localization of polysaccharides, including labeling with a fluorescent alginate probe. Histochemical staining allowed confirmation of a low alginate/fucoidan ratio in the cell wall indicated by exhaustive extraction of polysaccharides from the algal thalli. Alginate was located in the inner portion of cell walls. "Egg-box" structure of alginate in inner cortical cells may be related to the mechanism of algal growth. Abundance of fucoidan was confirmed by extraction on semithin sections and staining. Weak staining on nonextracted material was in agreement with previously proposed blockage of sulfate groups in these polysaccharides.

Abstract A detailed lipid characterization of Scenedesmus acutus PVUW12, with emphasis on the eva... more Abstract A detailed lipid characterization of Scenedesmus
acutus PVUW12, with emphasis on the evaluation of triacylglycerols (TAGs) as a biodiesel feedstock, is presented.When algal cells were grown in nitrogen-free medium (N stress), a lipid increase was detected that was mainly due to TAG accumulation. In situ fluorescence measurements allowed the kinetics and extent of neutral lipid accumulation to be followed. Under N stress, the productivity of total lipids and TAGs increased significantly (80.99 and 63.74 mg L−1 day−1, respectively) compared with controls (29.51 and
16.23 mg L−1 day−1, respectively). Monounsaturated fatty
acids were the major fraction and increased further
(49.74 %) in stressed cells, with oleic acid as the most abundant
compound (46.97 %). The polyunsaturated fatty acid
composition of this algal oil appears to meet the European
Standard EN 14214. These results indicate that S. acutus oil
meets the requirements for its use as a biodiesel feedstock.
Since this strain was also proposed for wastewater bioremediation, this opens up the possibility of its use in an integrated system combined with biofuel production

Bioresource Technology, 2012

The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enri... more The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enriched natural seawater, in order to assess its suitability as biodiesel feedstock. Optimal and nitrogen-stress (N-stress) conditions were analyzed. Under optimal conditions, the strain's growth rate was 0.73 div day À1 and the biomass concentration was 1.5 g L À1 , while it had a maximum lipid yield under N-stress conditions (lipid content: 26% of dry weigh and lipid productivity: 56 mg L À1 day À1 ). Lipid accumulation was mainly due to a significant increase of triacylglycerol content. Neutral lipids were characterized by a dominance of monounsaturated fatty acids and displayed a fatty acid profile that is suitable for biodiesel. This work offers an interesting alternative for sustainable microalgal oil synthesis for biodiesel production without using freshwater resources. However, further studies are necessary in order to optimize the lipid productivities required for commercial biodiesel production.

M. Cecilia Damiani , Cecilia A. Popovich , Diana Constenla , Ana María Martínez , Enrico Doria ,P... more M. Cecilia Damiani , Cecilia A. Popovich , Diana Constenla ,
Ana María Martínez , Enrico Doria ,Paolo Longoni ,
Rino Cella , Erik Nielsen,

Abstract: The development of effi cient, rapid and species-specifi c techniques is indispensable ... more Abstract: The development of effi cient, rapid and species-specifi c techniques is indispensable for assessing growth and neutral lipid yield in microalga cultures for biodiesel oil production. Nannochloropsis oculata is a small microalgae with a thick cell wall. In vivo techniques to estimate cell density, chlorophyll a and neutral lipids are reported. A calibration curve of cell density versus optical density was obtained and validated at 540 nm, under different growth phases. Intracellular neutral lipid storage was evaluated with fl uorometry and epifluorescent microscopy employing fl uorochrome Nile Red. The addition of 5 % dimethyl sulfoxide enhanced 12.5 times the fl uorescence signal effi ciency. In situ fl uorescence measurements allowed estimating the neutral lipid content (NR-FI). Besides, no signifi cant differences were found in the lipid neutral content between gravimetric and triolein methods. The relationship between NR-FI and chlorophyll fl uorescence signals was used as a neutral lipid accumulation index, which is useful in order to establish the optimum harvesting time. Thus, these procedures may be applied for a better monitoring mode of growth and neutral lipid accumulation in N. oculata’s cultures at commercial scale.

The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enri... more The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enriched natural seawater, in order to assess its suitability as biodiesel feedstock. Optimal and nitrogen-stress (N-stress) conditions were analyzed. Under optimal conditions, the strain’s growth rate was 0.73 div day1 and the biomass concentration was 1.5 g L1, while it had a maximum lipid yield under N-stress conditions (lipid content: 26% of dry weigh and lipid productivity: 56 mg L1 day1). Lipid accumulation was mainly due to a significant increase of triacylglycerol content. Neutral lipids were characterized by a
dominance of monounsaturated fatty acids and displayed a fatty acid profile that is suitable for biodiesel.
This work offers an interesting alternative for sustainable microalgal oil synthesis for biodiesel production without using freshwater resources. However, further studies are necessary in order to optimize the lipid productivities required for commercial biodiesel production.

Journal of Applied Phycology, 2013

The diversity of epiphytes, their temporal abundance variation and the anatomical structure of ho... more The diversity of epiphytes, their temporal abundance variation and the anatomical structure of host-epiphyte interfaces were studied in the agarophyte Gracilaria gracilis from a natural bed in Bahía Bustamante, Chubut Province, Argentina. Twenty-nine algal species were recorded as epiphytes during 2 years of monthly sampling (March 2006-February 2008. Total epiphyte density ranged between 0.037 ind. cm −2 (November 2006) and 39.37 ind. cm −2 (April 2007), with higher density values throughout the second sampling year. Ceramiales species were the most abundant epiphytes. The density of Ceramium rubrum ranged from 0.09 ind. cm −2 (52 % of the total amount) in September 2006 to 17.4 ind. cm −2 (44.18 % of the total amount) in April 2007. Epiphyte infection was more dependent on spore recruitment and sporeling development, especially on thalli derived from fragmentation, than on seasonal environmental variations.

Revista de la Sociedad Argentina de Biología

Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of d... more Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of detached thalli cast on the shore. Therefore, the study of carpospores is relevant because such spores can be used as inoculum for commercial aquaculture. In this study, the potential of two natural substrates from the Patagonian coast, for the settlement and growth of G. gracilis carpospores, was evaluated in the laboratory. Highly significant differences were found between substrates both in the proportion of substrates with settled spores and in carpospore density, shells being more suitable than pebbles. Regarding carposporeling growth, differences in sporeling length between substrates could not be detected by the end of the study, although basal discs reached a significantly higher diameter on pebbles than on shells. Results indicate that shells would be a good substrate to start spore culture because they offer a suitable surface for spore settlement. In addition, if the substrate is inoculated with sufficient seedling material to avoid competition among individuals and, if epiphytism is successfully reduced, sporelings should reach the required size for transport to the natural environment.

Biocell: official journal of the Sociedades Latinoamericanas de Microscopía Electronica ... et. al

This is the first comprehensive ultrastructural study on dwarf males with external gametangia in ... more This is the first comprehensive ultrastructural study on dwarf males with external gametangia in the genus Oedogonium, from androspore germination to the liberation of mature male gametes. The ultrastructure of the process in O. macrandrium Wittrok is similar to that of Bulbochaete hiloensis (Nordstedt) Tiffany, but with two remarkable differences. In O. macrandrium : 1) instead of a true transverse wall, only condensed mucilage appears between the gametes of each antheridial cell, and 2) the cell wall between the basal cell and the basal most antheridial cell has sim-the cell wall between the basal cell and the basal most antheridial cell has simple plasmodesmata similar to those present in the transverse walls of vegetative cells, which are absent in B. hiloensis.

Aquatic Botany, 2015

The ultrastructure of vegetative internodal cells in a representative of the genus Tolypella (sec... more The ultrastructure of vegetative internodal cells in a representative of the genus Tolypella (section Rothia) is described for the first time for Tolypella intricata. The most striking difference compared with the cells of Chara and Nitella is that the four-layered lateral cell wall shows the regular presence of unique refractive lenticular thickenings, which we designate as "tolysomes", considering their unique ultrastructure elucidated here for the first time. Tolysomes greatly amplify the plasma membrane surface; thereby defining particular spaces of the cytoplasm. There are similar structures in the cell walls of the non-charalean charophyte Coleochaete orbicularis and also in bryophytes, angiosperms and gymnosperms. As the function of tolysomes is hitherto elusive, a bona fide analysis of evolutionary significance is not yet possible. C-shaped amitotic nuclei are similar to those described for young internodal Chara cells. Resting amitotic nuclei exhibit normal nuclear envelope, dispersed granular chromatin and numerous nucleoli with variable size. Nevertheless, they show neither the single, central nucleolus characteristic of dividing Chara nuclei nor the bundles of tubular elements running parallel to the long axis of the nucleus, which are also normal in Chara and Nitella amitotic nuclei. The presence of C-shaped resting nuclei of Tolypella and Chara and their absence in Nitella and the presence of spindle-shaped nuclei in Nitella, but not in Tolypella, suggest that Tolypella (section Rothia) divergence took place earlier than did Nitella in accordance with, but also in contradiction to molecular data. Mature echinoid bodies and chloroplasts in Tolypella intricata are entirely similar to those previously described for Chara and Nitella.

Journal of Phycology, 2000

Journal of Phycology, 2000

Page 1. PSA ABSTRACTS 1 1 FATTY ACIDS IN PHOTOTROPHIC AND MIXOTROPHIC GYRODINIUM GALATHE-ANUM (DI... more Page 1. PSA ABSTRACTS 1 1 FATTY ACIDS IN PHOTOTROPHIC AND MIXOTROPHIC GYRODINIUM GALATHE-ANUM (DINOPHYCEAE) Adolf, JE1, Place, AR2, Lund, E.2, Stoecker, DK1, & Harding, LW, Jr 1,3 1Horn Point ...

Botanica Marina, 2000

Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of d... more Gracilaria gracilis is an important agarophyte that is exploited in Argentina by the harvest of detached thalli cast on the shore. Therefore, the study of carpospores is relevant because such spores can be used as inoculum for commercial aquaculture. In this study, the potential of two natural substrates from the Patagonian coast, for the settlement and growth of G. gracilis carpospores, was evaluated in the laboratory. Highly significant differences were found between substrates both in the proportion of substrates with settled spores and in carpospore density, shells being more suitable than pebbles. Regarding carposporeling growth, differences in sporeling length between substrates could not be detected by the end of the study, although basal discs reached a significantly higher diameter on pebbles than on shells. Results indicate that shells would be a good substrate to start spore culture because they offer a suitable surface for spore settlement. In addition, if the substrate is inoculated with sufficient seedling material to avoid competition among individuals and, if epiphytism is successfully reduced, sporelings should reach the required size for transport to the natural environment.

Bioresource Technology, 2009

Milled summer thalli of Gracilaria gracilis from Argentina were sequentially extracted with water... more Milled summer thalli of Gracilaria gracilis from Argentina were sequentially extracted with water at room temperature (RTW1-3), 70°C (W701-3) and 90°C (W901-2). Both W701 and W901 consisted of high molecular weight polysaccharides (ca. 540,000 Da), but polydispersity was higher for the major product W701 (yield, 72% of the recovered). Structural analyzes by methylation and 13 C NMR spectroscopy revealed that W701 was mainly agarose. Alkaline treatment, together with structural analyzes, indicated a negligible proportion of precursor L-galactose 6-sulfate residues in this product, while they were clearly detected in the 13 C NMR spectra of RTW2-3. The presence of floridean starch in W901 had an antagonistic effect on its gel strength, which resulted nearly three times lower than that of fraction W701.

Darwiniana, 2003

... Academic Press, London, Orlando. Lokhorst, GM, Bakker, ME & Star, W. 1984. Ultrastructure... more ... Academic Press, London, Orlando. Lokhorst, GM, Bakker, ME & Star, W. 1984. Ultrastructure of Draparnaldia glomerata (Chaetophorales, Chlorophyceae) II. Mitosis and cytokinesis. Nord. J. Bot. 4: 553-562. ... Arch. Protistenk. 112: 365-375. McLean, RO & Benson-Evans, K. 1977. ...

Phycological Research, 2013

Seasonal variation of agar from specimens of a commercially exploited population of Gracilaria gr... more Seasonal variation of agar from specimens of a commercially exploited population of Gracilaria gracilis (Stackhouse) Steentoft, Irvine & Farnham in the Patagonian coast of Argentina was studied. For each seasonal harvest, random samples of plants were pooled for subsequent polysaccharide extraction at different water temperatures and agar physico-chemical properties and composition were determined.

Journal of Phycology, 2000

The ultrastructure of zoospores of Asterococcus superbus (Cienk.) Scherffel was studied to provid... more The ultrastructure of zoospores of Asterococcus superbus (Cienk.) Scherffel was studied to provide ultrastructural data relevant to the systematic position of the genus. Our results demonstrated that the motile cells of A. superbus were similar to those of the tetrasporalean algae, such as Tetraspora sp. and Tetrasporidium javanicum Moebius . The flagellar apparatus of A. superbus had the same clock-wise orientation of basal bodies and the V-shaped alignment of basal bodies as Tetraspora cylindrica (Wahlb.) Ag. and T. lubrica (Roth) Ag., but differed by having rhizoplasts . The motile cells of A. superbus displayed chlamydomonadal ultrastructure, similar to Chlamydomonas reinhardtii Dangeard , including the absolute configuration of the flagellar apparatus. The pyrenoid matrix in A. superbus, however , showed a large lateral invagination occupied by chloroplast stroma, a characteristic that has never been observed in Chlorophyta.

Phycologia, 2007

ABSTRACT The chemical composition of the sporophyte cell wall of Adenocystis utricularis was exam... more ABSTRACT The chemical composition of the sporophyte cell wall of Adenocystis utricularis was examined by using a number of histochemical techniques for the localization of polysaccharides, including labeling with a fluorescent alginate probe. Histochemical staining allowed confirmation of a low alginate/fucoidan ratio in the cell wall indicated by exhaustive extraction of polysaccharides from the algal thalli. Alginate was located in the inner portion of cell walls. "Egg-box" structure of alginate in inner cortical cells may be related to the mechanism of algal growth. Abundance of fucoidan was confirmed by extraction on semithin sections and staining. Weak staining on nonextracted material was in agreement with previously proposed blockage of sulfate groups in these polysaccharides.

Abstract A detailed lipid characterization of Scenedesmus acutus PVUW12, with emphasis on the eva... more Abstract A detailed lipid characterization of Scenedesmus
acutus PVUW12, with emphasis on the evaluation of triacylglycerols (TAGs) as a biodiesel feedstock, is presented.When algal cells were grown in nitrogen-free medium (N stress), a lipid increase was detected that was mainly due to TAG accumulation. In situ fluorescence measurements allowed the kinetics and extent of neutral lipid accumulation to be followed. Under N stress, the productivity of total lipids and TAGs increased significantly (80.99 and 63.74 mg L−1 day−1, respectively) compared with controls (29.51 and
16.23 mg L−1 day−1, respectively). Monounsaturated fatty
acids were the major fraction and increased further
(49.74 %) in stressed cells, with oleic acid as the most abundant
compound (46.97 %). The polyunsaturated fatty acid
composition of this algal oil appears to meet the European
Standard EN 14214. These results indicate that S. acutus oil
meets the requirements for its use as a biodiesel feedstock.
Since this strain was also proposed for wastewater bioremediation, this opens up the possibility of its use in an integrated system combined with biofuel production

Bioresource Technology, 2012

The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enri... more The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enriched natural seawater, in order to assess its suitability as biodiesel feedstock. Optimal and nitrogen-stress (N-stress) conditions were analyzed. Under optimal conditions, the strain's growth rate was 0.73 div day À1 and the biomass concentration was 1.5 g L À1 , while it had a maximum lipid yield under N-stress conditions (lipid content: 26% of dry weigh and lipid productivity: 56 mg L À1 day À1 ). Lipid accumulation was mainly due to a significant increase of triacylglycerol content. Neutral lipids were characterized by a dominance of monounsaturated fatty acids and displayed a fatty acid profile that is suitable for biodiesel. This work offers an interesting alternative for sustainable microalgal oil synthesis for biodiesel production without using freshwater resources. However, further studies are necessary in order to optimize the lipid productivities required for commercial biodiesel production.

M. Cecilia Damiani , Cecilia A. Popovich , Diana Constenla , Ana María Martínez , Enrico Doria ,P... more M. Cecilia Damiani , Cecilia A. Popovich , Diana Constenla ,
Ana María Martínez , Enrico Doria ,Paolo Longoni ,
Rino Cella , Erik Nielsen,

Abstract: The development of effi cient, rapid and species-specifi c techniques is indispensable ... more Abstract: The development of effi cient, rapid and species-specifi c techniques is indispensable for assessing growth and neutral lipid yield in microalga cultures for biodiesel oil production. Nannochloropsis oculata is a small microalgae with a thick cell wall. In vivo techniques to estimate cell density, chlorophyll a and neutral lipids are reported. A calibration curve of cell density versus optical density was obtained and validated at 540 nm, under different growth phases. Intracellular neutral lipid storage was evaluated with fl uorometry and epifluorescent microscopy employing fl uorochrome Nile Red. The addition of 5 % dimethyl sulfoxide enhanced 12.5 times the fl uorescence signal effi ciency. In situ fl uorescence measurements allowed estimating the neutral lipid content (NR-FI). Besides, no signifi cant differences were found in the lipid neutral content between gravimetric and triolein methods. The relationship between NR-FI and chlorophyll fl uorescence signals was used as a neutral lipid accumulation index, which is useful in order to establish the optimum harvesting time. Thus, these procedures may be applied for a better monitoring mode of growth and neutral lipid accumulation in N. oculata’s cultures at commercial scale.

The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enri... more The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enriched natural seawater, in order to assess its suitability as biodiesel feedstock. Optimal and nitrogen-stress (N-stress) conditions were analyzed. Under optimal conditions, the strain’s growth rate was 0.73 div day1 and the biomass concentration was 1.5 g L1, while it had a maximum lipid yield under N-stress conditions (lipid content: 26% of dry weigh and lipid productivity: 56 mg L1 day1). Lipid accumulation was mainly due to a significant increase of triacylglycerol content. Neutral lipids were characterized by a
dominance of monounsaturated fatty acids and displayed a fatty acid profile that is suitable for biodiesel.
This work offers an interesting alternative for sustainable microalgal oil synthesis for biodiesel production without using freshwater resources. However, further studies are necessary in order to optimize the lipid productivities required for commercial biodiesel production.